re: swarms of microbots

Interestingly, I read an article a while back about the US military working on building microbots that could be scattered over a battlefield to be used for gathering images and sussing the lay of the land. The software and radios that they had were capable of self-configuring into an ad-hoc mesh network, so that part of it should be easy to sort out, even if a significant fraction of the machines don't survive the landing or fail in some other way.

As Helena points out, though, these things aren't really of any use as roving devices. There's a limit to how small you can make remotely-controlled bots while still giving them useful locomotion and other more practical sensors and actuated abilities.

Still, I think the microbot idea could still be pretty useful for future missions as a means of getting an initial idea of local terrain and even provide telemetry data for later, more fully-featured rover landings. The thought of sending an Internet to Mars is pretty cool too, especially if it can self-organise and do a kind of terrain "interferometry" (a fancy word for building a map from multiple viewpoints) locally instead of having to pipe everything back to Earth first. Think about it... Martian Internet! What's not to like about that?

"the unpredictable rocks on Mars"

I was a bit confused by this at first until I realised "unpredictable" was used in the sense of "No one could have predicted, in the first years of the twenty-first century, ..." Hooray for word-sense disambiguation!

LOL

Gotta love the unintended (I guess) hilarity of seeing the "Illicit phone rings in Sri Lankan inmate's back crack" article cheek by jowl with the "BYOD is a PITA" one ... or are the Reg editors having a bit of fun today?

fraction schmaction

Wall Street responded by pushing the social networking firms shares to $150, significantly up from their IPO price of $45. By contrast, Facebook's shares still languish at around two-thirds of their IPO price, and those (un)lucky enough to buy into Groupon and Zynga have seen their holdings reduced to a fraction of their initial value.

I'll have you know that 2/3rds is also a fraction! Then again, so is 150/45, but I don't want to be too pedantic...

Re: Rubbish comments system

Stop splitting the site sections to look like different websites, for fuck sake.

It's worse than that. Even though we can all still click on the comments link to see the entire thread the way we've been used to, there are at least a few bad knock-on effects I predict will be the result of the new system:

1. We'll get many more first-post click whores who are more interested in just getting their words underneath the article than engaging in a conversation (ie, what the comments section is). It doesn't really matter how inane the first poster is, the fact that they're first means they have an advantage when it comes to click whoring.

2. Even those posts that are genuinely interesting and get lots of votes probably won't make very much sense in isolation since, again, it needs the full conversation as context (at least unless people change their posting styles to incorporate quotes so people know what the immediate context is)

3. We'll get lots of stupid/redundant replies in the comments section based on people attacking/defending comments that they read in the main article page without checking whether it's already been done to death in the main comments page (again with the idea of a "conversation"... get the picture?)

If the reg must have "promoted" comments (or "highly rated" as it's called now), you should either copy what Ars does and let the editors pick and choose what comments are promoted OR you add a new button to the current roster of thumbs up/thumbs down to indicate that a comment is both worthy AND front-page material (I suggest a thumbs up icon in front of a star). I'd hope that people would realise the point of the new icon is to flag posts that are particularly insightful and self-contained enough to act as a companion to the story, but who knows... you'd really have to try it to see how it works. At least it couldn't be worse than the new system.

Actually, it depends. I prefer loose leaf tea to tea bags (*), but I drink more bagged tea due to the convenience. Anyway, if you make a proper brew(**) you need to scald the pot, put in the leaves and then put in the boiling water. If you've faffed around for too long between starting and pouring in the water, boil it up again then put it in the pot. It needs to be boiling(**). Then put it on a hot stove for about 4-5 minutes. For this type of tea, you absolutely need to put the milk in the cups first, otherwise you scald the milk. You might not believe this, but do a blind taste test and I think you'll be able to tell the difference.

For bags, you also need boiling hot water to begin with (and you may also wish to scald the cup first so it stays hotter, but it's not necessary), but from that point on you just leave it to brew by itself for a couple of minutes. Personally, I give it a stir (usually by grabbing the back with my fingers and swirling it around, but you can be fancy and use a spoon) and remove the bag before adding the milk, but the other variations of this aren't wrong. The only thing I'd insist on is if you have to use a sweetener, then it has to be honey. Even then, sweetener is really only something you want after some kind of shock or a day's hard labour, in which case it's acceptable :)

* Barry's Tea is de rigeur; it's a blend, but mainly based on Assam (also called Breakfast Tea by many)

** Actually there are many "proper brews", but I'm talking about black (fermented) leaf tea here. That's not to say that things like green/gunpowder/matcha tea (which don't take kindly to boiling water at all), Oolong or even (horror of horrors) mugi cha (which actually isn't a "tea" at all) aren't all worthy beverages in their own right.

*** Incidentally, this is why it's hard to make a decent cup of black leaf tea at altitude since the boiling point is reduced. Green (unfermented) tea is much better there.

Re: It's not a proper mug of tea unless it's a double bagger

Until, after many months, you are forced to leave half a dish washing tablet in the mug overnight to remove the build up of tea scale which has reduced the volumetric capacity of said mug to the point of unusability

Rinse the cup out in water, so that there's a dribble of water in it. Pour in some table salt and rub it over the tea stains. No need for a storm (or chemical warfare) in a teacup.

Re: Eye Spy with My Raspberry Pi

Re: Don't you know, the PI itself is the loss leader

Actually, according to a recent interview, Eben Upton said that everyone in the supply chain is making a profit. I assume that the distributors also take a small/tiny cut. Granted, like you said, they are using the Pi to entice you to buy items they're making more profit on, but technically it's not a loss leader if they don't make losses on the Pis.

Re: Agree

Playing with a web server on my home connection isn't the greatest idea in the world

Learn how to set up a Demilitarised Zone (DMZ) on your network. Simply put, you make a separate subnet for your web server and use IP filtering rules (at your router) to allow machines outside that subnet to access it, but block all outgoing traffic (apart from responding to already-established connections initiated from other hosts). It can be as simple as three iptables rules: one default rule drops all forwarded traffic, one allows NEW connections to be forwarded to the DMZ box and a third allows packets that are ESTABLISHED or RELATED to be forwarded from the DMZ box. In practice, you'll probably want to do something more complicated, like doing NAT masquerading and port-forwarding at the router (so that all your machines appear to be at the same IP address and so that traffic coming from the Internet on port 80 is forwarded to the DMZ machine, respectively) so I can't give you the exact iptables commands or other firewall rules here.

Likewise, if you need to allow the DMZ machine to access certain services inside your network (that you can't or don't want to store on the DMZ machine) then you need to add more rules to allow it to make those connections. You'll want to lock down that service so that the DMZ machine can only do the bare minimum with it that it needs to operate without leaving a big hole in your security. Or better yet, migrate a minimal version of the service to the DMZ box itself or another machine on the DMZ subnet. There's always a trade-off between security (risk of the machine getting hacked) and utility (eg, you'd really like to be able to access your IMAP server) with any machine connected to the net, but a DMZ is a nice way, up to a point, to get the best of both worlds.

So basically, look up setting a DMZ for your particular router and learn about how to set up firewall rules in general.

Other than that, your distro should have packaged the web server to be pretty secure already, such as running it as a user with restricted rights (nobody in Unix-based systems) and maybe it also gives you the option of running in a chroot jail too.

Samsung make fridges like many other people, make TVs like many others, make everything like many others - even phones. There is nothing special about their stuff - it's ok but functional and you buy a Samsung today and you may but a Samsung whatever next time but no real compelling reason.

They are happy selling a box today and banking the cash but it's not really long term - they sell an Android phone and pass you on to Google for future revenue.

According to the recent article here Samsung started "in 1938 as a company selling dried fish and vegetables, and moved into electronics in the late 1960s". OK, maybe the dried fish and vegetables were only "functional" and there was no real compelling reason to buy Samsung dried fish and vegetables the next time.

But consider that they're now one of the top companies in Korea (if not the top, judging by the fact that their top man is the richest guy in the country). Do you really think that the sort of business minds that brought the company from such lowly beginnings doesn't have long-term aspirations? Do you really think that they don't care about, eg, their Galaxy range, and that they'll happily "pass you on to Google for future revenue"?

Could you imagine Bill Gates or Steve Jobs having that attitude? Is it even conceivable that Samsung won't do all it can to keep and expand its customer base?

Finally, one non-rhetorical question: is it possible that Apple pays people to pollute discussions like this with drivel like yours? Absolutely.

printing from lunar soil?

Re: Three Strikes?

Sorry to reply to my own post, but it just occurred to me that they try for a charge of "contributory infringement" if they can prove that the user was uploading to a torrent swarm as well as downloading. In regularl language I suppose that means that the torrent user is helping other torrent users to copy something illicitly. Makes a lot more sense than the argument I've seen with some cases that each pirated copy is responsible for some crazy number of lost sales due to the uploading part. I could never get my head around how they could even claim that with a straight face. Mathematically, ff that were true, we'd have an infinite number of illicit copies for every one that was paid for.

Re: Three Strikes?

Hmm... it still doesn't compute. Aren't the warnings of the "cease and desist" variety? If so, how can she have received three warnings for downloading two songs? Did she like one of them so much she tried to download it again even in the face of the first two warning letter?

Also, on a different point, even if the RIAA (or equivalent) had rootkits on everyone's computers, would it even be possible for them to make the argument of uploading stick? I mean, technically, yes, anyone who's connected to a torrent will upload to some degree, but aren't most users (ie not the long-term seeders) just in it to download stuff? I really don't know how this separate uploading argument is supposed to work if regular users are just helping other torrent users to download.

Re: Probability

If you had 50 marbles, numbered 1 to 50, there would be a 10% chance of selecting a specific desired number with any 5 random selections from a set of 50. So 43% is only four times better than random guessing. Does the software know what the valid 50 numbers are, and pick the closest match? If so, the results are not impressive.

Whoa there... the number 50 is the size of their test sample, and nothing to do with the number of possible PINs, so your probability calculation is meaningless. In other words, their program is being asked to guess what the PIN is, and not "guess which one of these 50 known patterns/PINS" we've given you".

The way you should look at it is that each random PIN guess (having no accelerometer hints) would be right 1/10,000 of the time (ie, 0.0001). If they can guess the PIN 43% of the time with 5 guesses, then their success rate per guess is 0.43 / 5 or 0.086. So in fact their ability to guess a PIN is actually 0.086 / 0.0001 = 860 times better than chance, not four times better!

Re: The G Bomb!

Re: The G Bomb!

What exactly is the need for this? You know one of the Japanese words for foreigner ... "offensive" foreign word..

Pah. "Gaijin" is only offensive if it's used in a way that's meant to be offensive. That hardly applies here. I couldn't care less if someone calls me a 外人 or a 外国人. Or a Paddy or Mick, for that matter. You should save your ire for someone who's being deliberately offensive to you.

Re: But this future will never come

So I'm not so hopeful that it'll all fit in memory...

There's been a trend in research systems at least towards looking at using RAM to store index information while delegating actual data storage to (flash) disks. FAWN-DS (Fast Array of Wimpy Nodes Data Store), for example, reduces the amount of RAM used by each index entry to 6 bytes, while SILT (Small Index, Large Table) achieves even more compression of those index data (somewhere between 1.5--2.5 bytes per index entry, iirc). It also helps that these systems are designed from the ground up to work well with flash storage and avoid the write amplification problem (where a single write requires several physical writes due to the need to rewrite entire memory blocks when a single page changes). I'm not sure how many of these design features are implemented in today's commercial-grade systems (like hadoop's file system) but I'd wager that there are more similarities than differences.

If you add to this the fact that clustering your storage nodes is relatively easy using consistent hashing (or a DHT) to spread the storage across many nodes/controllers each with their own RAM and local storage, then I think that such a future is actually quite practical today. A lot more practical than you think.

Re: Analogy failure...

"You can tell everybody to get out of their trucks (TCP) and get on motorbikes (the new thing) congestion isn't as bad, no need for the traffic lights at every junction, and no expensive lanes being added."

Or you can have everyone get out of their car/truck/bike and move forward one vehicle. Hows about that? Guaranteed progress even in the face of deadlock....

Re: Good to know my physical links are now 2000% efficient

I think other posters have already covered that the paper's authors are only claiming improvements over high-latency links (and fairly lossy ones at that). The fundamental problem with TCP over such links is that each TCP packet needs to be acknowledged so (having a sliding window for acks notwithstanding) transmission speed is fundamentally limited by how fast and reliably the acks can be sent back.

Some guys at Microsoft tested out another scheme for improving transfer speeds over high-latency links (though they assumed low packet loss) a few years ago. It worked by the receiver sending ACKs to some number of packets it hadn't actually received yet, thus fooling TCP's flow control mechanism into avoiding its normal exponential backoff algorithm. That trick obviously only works over reliable data links with very little packet loss. I don't have a link to that paper, but ISTR that it was covered here on The Register. No doubt it also got its share of comments along the lines that you're making here (ie, >100% efficiency).

Re: Yet another bad research paper

With UDP you can just keep sending data. Provided the far end sends back relevant acknowledgments you might be able to get away with only a few re-sends.

Alternatively, you can use forward error correction to eliminate the need for a lot of "back traffic" (or "packets traveling in the wrong direction which often hamper UDP communications" as the article states). Have a look at the udpcast project for an example of that. It's designed for multicast, where the problem with ack storms is much more severe, but it seems that with a little tuning it should be also be pretty efficient to use it for point-to-point transmissions too. There are also, IIRC, a couple of competing RFCs for implementing reliable delivery over UDP channels, and they include flow control algorithms as a means of congestion avoidance (similar to what's described in the article).

I think the most interesting thing about this paper seems to be how they convert everything to use their new UDP protocols. It seems like a good approach given that it's much simpler to implement congestion avoidance and flow control if everything is based on the same underlying transmission protocol. It does sound a bit drastic, though.

Re: Quite impressive in term of size but am I alone in wondering.

Shouldn't this SIMD thing just work by now instead needing lots of twiddling?

It's not just SIMD. Although the article doesn't state it explicitly, each of the cores models a small area of space and it has to communicate various outputs to neighbouring small areas of space. The clue is in the line The waves propagating throughout the simulation require a carefully orchestrated balance between computation, memory and communication. Amdahl's Law puts a brake on how well any real-world computation like this will scale up when run on a parallel (or SIMD) architecture due to the need for components to interconnect and transfer data between each other (such as propagating global force/pressure vectors after each local computation per simulation time quantum) . In this case, I'm sure a lot of their time spent "ironing out the wrinkles" was trying to get those inter-core messaging parts of the simulation humming. But there are other potential bottlenecks too that need to be looked at to prevent stalls/starvation too (ie, "computation, memory and communication" above). There's definitely not just a single "point and shoot" solution to parallel programming.

Re: @Frumious Bandersnatch

Thanks, Daniel B. It's nice to have that validated, even down to my guess that private and public keys don't store the same data . The downvotes I got are unimportant compared to that. Now if Lee Dowling had said that p and q were stored with the private key then I'd happily have conceded the point to him. Maybe he knew that and it's what he was trying to get at, but it's not what came across. I'll give him the benefit of the doubt and say we're all right. Except the downvoters. You still suck.

Re: but ...

No, they are not equivalent. Maths modulo high primes is the entire security BECAUSE it's not a mechanism that you can just reverse like that, and the private key is not "just a prime".

In general, the private key contains both the public key and some other large prime, whereas the public key is only a large prime (to get a simple analogy). The public key is actually derivable from the private key (that's how you MAKE a public key!) but NOT vice-versa (or PKE encryption would be useless). The private key contains extra, private information that should not be revealed and is not in any way derivable from the public key within a reasonable length of time.

OK, so I just happened to have Schneier's Applied Cryptography (2nd edition) on my desk as I read your post. I looked it up and confirmed that what I said earlier is correct. On page 467 it covers generating the public and private keys (which are multiplicative inverses of each other mod (p-1)(q-1)). Then it talks about encrypting and decrypting and finishes by saying "The message could just as easily have been encrypted with d and decrypted with e; the choice is arbitrary". That's exactly (and only) what I said in my post. I think you may need to brush up on how RSA encryption works. In particular, you can't derive either the public key from the private key, or vice-versa. Not without knowing the factorisation of pq, anyway. Nor does the private key contain "extra, private information".

Compound encryption schemes (involving RSA and something else) are a different matter, as you pointed out. But then, I never actually claimed that you could swap keys there and still have everything work.

but ...

isn't ((m ** private) ** public) mod pq = ((m ** public) ** private) mod pq? Maybe some of these users at least have just decided to swap public and private keys for each other? Maybe it's their secret "twist"...

OK, I'm not really serious. Most likely ssh (or pgp or whatever you use to generate keys and do the crypto) stores public keys in a different format to the private key so they're not interchangeable. But at least with the underlying RSA bit, calling one key public and the other private is just a matter of which one you actually reveal...

what did it calculate?

I like widescreen too, for the reasons already pointed out. I still find myself wishing for more vertical resolution too, though. Tabbed browsing in the webotron and gnome-terminal (and virtual desktops if you want to count that) already make great use out of screen real estate, but it would be nice to be able to see more lines of code in emacs or Eclipse or the like. Come to think of it, I guess there's always Ctl-x 3 in emacs if I want to look at a buffer in 2-up mode, providing I don't mind scrolling manually in each window. I must remember to try that next time.